So you Wanna . . . . . . . , Installment #2
FINISHING
GLUING
STRENGTH
HINGES
ELECTRONICS
CONTROLS
PROP SAVERS
VELCRO
Well, if you're still interested enough to come to this page, then I guess I better keep going! Again, these are my personal views, and many may choose to disagree with them. And again, "Cheapness keeps me in the game" is my motto, so if I can save a buck here and there, I'm going to.
As mentioned last time, I like the 'FoamyFactory.com' designs, and here are the two that I mentioned:
I've already discussed the 'BlueCor' material, and here it is. The decorations were created with a $10 package of markers, they are called 'Sharpies', and do a GREAT job. If you shop at a large craft store (like A.C.Moore), they are also available in different sizes. Get a BIG black one, it really pays off.
THEY CAN be painted, but BE CAREFUL! My first 3D was a work of art, BEAUTIFUL cuts on the foam, etc.. Then I decided to use some spray paint I had, a nice shade of red. The end result was a red blob of plastic that merely RESEMBLED what I started with.
Any paint containing 'toluene', acetone, or lacquer won't work! Latex is OK, as are true acrylics. ALWAYS test a scrap piece piece of foam first. However, do you really want the extra weight? Try it simple first, see how it flys, then build another one. BOTH of these are made with $1 worth of BlueCor.
When gluing these things, REGARDLESS of the glue chosen, it's a good idea to remove the 'skin' for better adhesion. Be careful to apply ONLY enough pressure to cut the skin, and NOT the underlying foam.
I will mention at this time that you'd better buy a BIG package of #11 Xacto blades, because as soon as they begin to dull, the foam 'bunches up', instead of making a clean cut. Use of a 'self-healing', or soft mat underneath minimizes this, but you still need a lot.
'Foam-Safe CA' works, but my personal preference is STILL the 'lo-temp' hot glue gun and sticks. After a while, you gain the ability to use the proper amount for a good joint, with very little 'spill-over'. If you're not that picky, you can do a little 'pre-heat' of the joint afterwards, and lay down a nice bead for even more strength.
Foam is NOT the strongest material in the world, and needs a little help on long spans such as the wing(s) and fuse. Many plans call for 'carbon rods', but you can cheat quite a bit in this area. If you look REAL close at the wings of the 3D. you can see 2 long pieces of '3M Filament Reinforced Packing Tape'. This is run full span, one piece (unbroken), and stiffens the wing enough for this design, and similar models. Some designs call for application of the carbon rods/tubes to leading/trailing edges to accomplish the same thing. If you would like it even stiffer, put two on the bottom as well:
The plans for the 3D use a foam stiffener for the fuselage stiffener, whereas the Ultimate Bipe calls for a carbon rod. GUESS WHAT, foam is CHEAPER, so I used it on the bipe too. My modification is 2" wide at the nose, and 1" at the tail. Cut it as shown, and make matching cut-outs in the fuse to lock it all together:
"Gee, he only used ONE strip of tape on the bottom"! Right, but the load (small as it is), is spread between 2 wings, so it works out OK. As far as the 'black thing', it's a piece of spare carbon rod to absorb MOST of the landing rash (Oh yeah, it doesn't have any WHEELS).
Now, the carbon stuff 'ain't cheap', so I looked for an alternate source, and here are two (thank me later). Find an outfit that builds/repairs fishing rods, and get a free source of some carbon. Yes, they will be tapered, but SO WHAT. Free is great. Another source when you really begin experimenting with your own design 'stick' models will be arrow shafts, I got mine for $1 apiece.
Now here's one that will REALLY surprise you! Steal the 'Scotch Magic Mending Tape' from the desk, take it into your shop, and make a GREAT hinge. Cut a 45 degree wedge from the moveable surface, and tape it all together. Full span on the top, but DON'T use full span on the bottom, just a few scattered pieces (too stiff otherwise).
Here, I will tell you what I did, but I should mention that I'm an Electrical Engineer by trade, so I have a pretty good idea of what's going on. As a 'newbie', I searched the web (Internet) for as much info as possible.
MOTOR
I decided early on that I was going to go brushless, direct drive, because the fewer moving parts that are involved in a drive train, the better. I settled on a custom built outrunner that was assembled utilizing parts from 'gobrushless.com'. I picked a 'single stator' unit, wound 17 turns with #26 gauge wire. I am STILL impressed by the amount of thrust I can get with a 3S1P LiPo battery. Also, the design allows for great cooling, and they do need it.
BATTERY
My first pack was made by 'Apogee', and I must say is a quality unit. The individual cells were matched BEFORE assembly so that their characteristics would match, and facilitate the charging with connections to the 'end points', and not the individual cells. Since then, I have begun assembling my own, and keeping 'logs' of the individual cell performance characteristics. This is a LOT cheaper, and therefore allows me to simply switch packs, while the other one is charging.
ESC
There are several out there, but I chose the 'Castle Creations Phoenix 10' as my first. It will handle 10 amps CONTINUOUS, and 'surges' to 15 amps. I quote:
"As an aircraft ESC, the Phoenix-10 is superbly suited for micro flyers. With several cut-off choices to choose from, this little beauty has cut-off settings for 2, 3, and 4 cell Lithium Ion and Lithium Polymer packs, yet it works just as well with NiCad and NiMH cells. An optional brake, over-current protection, and a host of other features make this THE sensorless to own!"
The units individual features can be programmed IN THE PLANE by using your throttle stick as a 'yes/no' switch.
http://www.castlecreations.com/
It also supplies all the power for the receiver AND servos.
RADIO
Hey, your choice here. I fly with Futaba FP127DF receivers with the case removed, as well as a Hitec 555. The only comment I will make (again) is DON'T buy a single conversion unit, the weight gain/loss is not tworth the possible problems.
SERVOS
Hmmm, again, YOUR choice! I use servos from a Canadian outfit called 'Draganfly', their 9 oz. units are $10 apiece.
Wrong title, it should really be 'how to save weight and still control the model'. My personal preference is spring steel wire, .030" diameter. This matches with most of the newer plastic hardware becoming available, such as 'keepers', control horns, and servo arms. HOWEVER, it really does SPRING very well, and must be supported to avoid 'slop' in the controls. My way is shown here:
They are simply pieces of inner 'NyRod', glued on top of small foam spacers. Notice the use of both 'keepers, as well as the adjustabe connectors on the servo arms. Suggestion, replace the supplied screws with 4/40 allen head set screws, MUCH easier to handle/tighten. You will ontly have to punch a small hole through the wing to adjust the aileron servo. In these pics, ALL of the control horns are fabricated with short pieces of nylon 'ty-raps'. Again, I DO use the CA for gluing these.
These are MANDATORY when not using a landing gear, and as soon as you discover the big difference a little extra weight makes, you'll most likely go this way. Besides, there is NO way you're going to land in either grass or a rough surface. They are also knwn as 'wobblies', and are essentially a 'cone' shaped adapter that fastens to the prop shaft, and the prop is then held on to it with rubber bands. When the prop hits an obstacle (usually the GROUND), it simply 'lifts off' the cone, and bends back out of the way. It also saves a LOT of money on replacement motor shafts as well ($2.50-$4.00). Cost is a WHOPPING $2.50. I'm STILL trying to find a good source for the rubber bands, a #10 is too big. I'll chech with the Orthodontist next.
Final item in this installment. ALL of my gear except servos/motor is held on the plane with 1" squares of 'sticky-back' Velcro, I got mine at Staples. GREAT for swapping battery packs, receivers, etc. Use smaller 'strips' of these to act as wire hold-downs as well.
I hope this has been of some help to my fellow 'newbies', and I would appreciate ANY feedback you may care to offer. I hope to have input from other authors, and to add to this data as I discover sources. I'll probably open a separate section of the web site for this purpose, so 'stay tuned' for new stuff.
Bill Capes, fellow flyer and WebMaster
